Euro Carmakers Protest CO2 Proposals and then Parade Cars That Might Meet Them

The Steering Column

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Amid the glittering debuts at the Frankfurt auto show in September [see Upfront, page 35], there was a looming dread about the new carbon-dioxide regulations proposed by the European Parliament. The mandate would cut the average CO2 emissions of new vehicles to 130 grams per kilometer by 2012 (it was 162 grams in ’05). What that means is vehicles in Europe will have to average 43 mpg for gasoline engines and 48 mpg for diesels (diesel fuel contains more carbon per gallon than does gasoline). The 35-mpg CAFE standard proposed by the U.S. Congress seems mild by comparison.

Building such cars is hardly impossible. Renault recently introduced the Laguna 1.5 dCi, which is a Honda Accord–sized car that emits the requisite 130 g/km of CO2, thanks to a 109-hp, 1.5-liter diesel engine. But it needs about 12 seconds to reach 60 mph and is unlikely to be a hot seller, even in Europe where gasoline is running close to $7 a gallon.

The ACEA, the European automakers’ association, met at Frankfurt, and all the CEOs lined up on stage to present a united front in opposition to this new CO2 proposal. In particular, German carmakers are worried because their high-powered models have no chance of meeting the standard, given that most vehicles to be sold in 2012 are already in the design stage. At Porsche, for example, the lowest CO2 emitter in the current lineup is the Cayman five-speed, which puts out 222 grams of CO2 per kilometer—71 percent above the limit.

Given this background, fuel-stingy vehicles took the show’s spotlight—a plethora of lightweight cars, new-fangled engines, various tiny city-mobiles, and every manner of hybrid.

General Motors’ Opel division showed the Flextreme concept, which is essentially a Euro version of the Chevrolet Volt plug-in-hybrid concept. Being a Euro-mobile, it uses a 1.3-liter turbo-diesel engine to power its generator instead of the Volt’s small gasoline powerplant. Its onboard battery can provide up to 34 miles of electric-powered operation before this diesel fires up to recharge the lithium-ion cells. If your trips are shorter than 34 miles, the battery can be recharged in no more than three hours from a European 220-volt household outlet. On longer trips, the Flextreme is an efficient hybrid, getting roughly 150 mpg, which translates to expelling a minuscule 40 grams of CO2 each kilometer traveled. Combining an expensive turbo-diesel with the inherently costly plug-in hybrid concept makes little sense, but it does demonstrate that GM’s plug-in technology works with any engine that can spin a generator.

One of the most sophisticated high-efficiency concepts was the Mercedes F700, an S-class–sized car powered by something called the DiesOtto engine. The awkward name refers to a combination of a diesel engine and a conventional Otto-cycle gasoline engine. Everyone else calls such engines HCCIs (“homogeneous charge compression ignition”). Their claim to fame is combining the fuel efficiency of a diesel engine with the power and low cost of a gasoline powerplant. Running in the diesel-like compression-ignition mode up to about 2000 rpm, the engine burns lean, sips fuel, and produces a clean exhaust. At higher revs the twin-turbocharged 1.8-liter four-cylinder engine switches to spark-ignition mode and develops up to 235 horsepower and 295 pound-feet of torque­—enough to push the F700 from 0 to 60 mph in about 7.5 seconds.

The trick in HCCI engines is to maximize the time in the compression-ignition mode, where efficiency is greatest. To achieve this, the DiesOtto engine has a variable compression ratio that is achieved by means that Mercedes advanced engineering boss Herbert Kohler is unwilling to disclose. Further powertrain flexibility comes from a 20-hp electric motor that provides the F700 with hybrid capability. This motor not only supplies torque to move away smartly from a dead stop before the two-stage turbos are spooled up but also can be used to extend the HCCI operating regime.

The F700 gets 44 mpg, which works out to emitting 127 grams of CO2/km, and meets stringent smog emissions standards without requiring particulate traps and urea-activated catalysts. It suggests that large Mercedes models could potentially achieve very low CO2 emissions, provided the technological costs don’t exceed even Mercedes’ hefty manufacturing budget.

Porsche showed a hybrid in Cayenne form. It had a pancake electric motor attached near the flywheel of a V-6 automatic model. This is much like the arrangement used by Honda in its hybrids with one key difference: In the Porsche, the 46-hp electric motor can be decoupled from the engine so it can power the vehicle while the engine is stopped, up to 75 mph, although it’s slow in getting there. Being a rear-wheel-drive model, the hybrid Cayenne’s regenerative braking operates only on the rear wheels, but apparently, enough juice is recovered to keep the 288-volt Ni-MH battery, which resides in the spare-tire well, fully charged. The entire system adds about 333 pounds to the Cayenne, but Porsche is already achieving a 25-percent fuel-economy boost with it and expects to increase that to 30 percent when the hybrid goes on sale in three or so years.

Even the tuners got into the low-CO2 act. AC Schnitzer, a well-known BMW speed merchant, showed its GP3.10 Gas Powered. This is essentially a BMW 3-series coupe with the 5.0-liter V-10 from the big M performance cars shoehorned under its hood, souped up, and converted to run on LPG (liquefied petroleum gas) as well as gasoline. Burning LPG generates about 15-percent-less CO2 than does gasoline, although if you take advantage of the engine’s 544 horsepower to explore the car’s claimed 199-mph top speed, your carbon-dioxide output will not win any Sierra Club awards.